BS-7149-1990 EN-26373-1989 ISO-6373-1984.pdf

BRITISH STANDARD BS 7149:1990 EN 26373:1989 ISO 6373:1984 Specification for Programming language Minimal BASIC This European Standard EN 26373 has the status of a British Standard. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7149:1990 This British Standard was published under the authority of the Board of BSI and comes into effect on 31 August 1990 © BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference IST/5 Draft for comment 82/61564 DC ISBN 0 580 18663 6 Cooperating organizations The European Committee for Standardization, under whose supervision this European Standard was prepared, comprises the national standards organizations of the following Western European countries. AustriaOesterreichisches Normungsinstitut BelgiumInstitut belge de normalisation DenmarkDansk Standardiseringsraad FinlandSuomen Standardisoimisliito, r.y. FranceAssociation française de normalisation GermanyDeutsches Institut für Normung e.V. GreeceHellenic Organization for Standardization IcelandTechnological Institute of Iceland IrelandNational Standards Authority of Ireland ItalyEnte Nazionale Italiano di Unificazione LuxemburgInspection du Travail et des Mines NetherlandsNederlands Normalisatie-instituut NorwayNorges Standardiseringsforbund PortugalInstituto Portuguès da Qualidade SpainAsociación Española de Normalización y Certificación SwedenStandardiseringskommissionen i Sverige SwitzerlandAssociation suisse de normalisation United KingdomBritish Standards Institution Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7149:1990 © BSI 01-2000i Contents Page Cooperating organizationsInside front cover National forewordii Brief history2 1Scope and field of application3 2Conformance3 3References4 4Definitions4 5Characters and strings6 6Programs7 7Constants9 8Variables10 9Expressions11 10Implementation supplied functions13 11User-defined functions14 12Let statements15 13Control statements15 14For and next statements17 15Print statement19 16Input statement21 17Read and restore statements22 18Data statement23 19Array declarations24 20Remark statement25 21Randomize statement25 Annex A Organization of the standard28 Annex B Method of syntax specification28 Annex C Implementation-defined features29 Annex D Index of syntactic metanames30 National appendix AInside back cover National appendix BInside back cover Table 1 Values of implementation-supplied functions13 Table 2 BASIC character set26 Table 3 BASIC code27 Table 4 Index of synthetic metanames30 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7149:1990 ii © BSI 01-2000 National foreword This standard had been prepared under the direction of the Information Systems Technology Standards Policy Committee. It is identical with ISO 6373:1984 “Data processing Programming languages Minimal BASIC”, published by the International Organization for Standardization (ISO). In 1989 the European Committee for Standardization (CEN) adopted ISO 6373 as the European Standard EN 26373. The publication of BS 7149 is to meet the obligations of the United Kingdom as a member of CEN to give EN 26373:1989 the status of a national standard without modifications. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 34, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM EN 26373 March 1989 UDC 681.3.04:80092 BASIC Key words: Data processing, programming languages, basic, specifications English version Data processing Programming languages Minimal BASIC (ISO 6376, 1st edition, 1984) Traitement de linformation Langages de programmation BASIC minimal (ISO 6376 1ère édition, 1984) Datenverarbeitung Programmiersprachen Minimal BASIC (ISO 6376, 1 Ausgabe, 1984) This European Standard was accepted by CEN on 21 December 1988 and is identical to the ISO standard as referred to. CEN members are bound to comply with the requirements of the CEN/CENELEC Common Rules which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to CEN Central Secretariat has the same status as the official versions. CEN members are the national standards organizations of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comité Européen de Normalisation Europäisches Komitee für Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels © CEN 1989 Copyright reserved to all CEN members Ref. No. EN 26373:1989 E Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 26373:1989 © BSI 01-2000 2 Brief history The Technical Board has decided to submit the International Standard ISO 6373, 1st edition, 1985 “Data processing; Programming languages; Minimal BASIC” to the formal vote. The result of this vote was positive. For the time being, only the English and the French versions are available. According to the CEN/CENELEC Common Rules, the following countries are bound to implement this standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. Statement The text of the International Standard ISO 6373, 1st edition, 1984, was approved by CEN as a European Standard without any modification. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 26373:1989 © BSI 01-20003 1 Scope and field of application This International Standard is designed to promote the interchangeability of BASIC programs among a variety of automatic data processing systems. This International Standard establishes: a) the syntax of a program written in Minimal BASIC; b) the formats of data and the precision and range of numeric representations which are acceptable as input to an automatic data processing system being controlled by a program written in Minimal BASIC; c) the formats of data and the precision and range of numeric representations which can be generated as output by an automatic data processing system being controlled by a program written in Minimal BASIC; d) the semantic rules for interpreting the meaning of a program written in Minimal BASIC; e) the errors and exceptional circumstances which shall be detected and also the manner in which such errors and exceptional circumstances shall be handled. Subsequent International Standards for the same purpose will describe extensions and enhancements to this International Standard. Programs conforming to this International Standard, as opposed to extensions or enhancements of this International Standard, will be said to be written in Minimal BASIC. Although the BASIC language was originally designed primarily for interactive use, this International Standard describes a language that is not so restricted. The organization of the International Standard is outlined in Annex A. The method of syntax specification used is explained in Annex B. 2 Conformance There are two aspects of conformance to this International Standard: a) conformance by a program written in the language; b) conformance by an implementation which processes such programs. A program conforms to this International Standard only when each statement contained therein is a syntactically valid instance of a statement specified in this International Standard; each statement has an explicitly valid meaning specified herein; the totality of statements compose an instance of a valid program which has an explicitly valid meaning specified herein. An implementation conforms to this International Standard only when it accepts and processes programs conforming to this International Standard; it reports reasons for rejecting any program which does not conform to this International Standard; it interprets errors and exceptional circumstances according to the specifications of this International Standard; its interpretation of the semantics of each statement of a standard-conforming program conforms to the specifications in this International Standard; its interpretation of the semantics of a standard-conforming program as a whole conforms to the specifications in this International Standard; it accepts as input, manipulates, and can generate as output numbers of at least the precision and range specified in this International Standard; it is accompanied by a reference manual which clearly defines the actions taken in regard to features which are called “undefined” or “implementation-defined” in this International Standard. This International Standard does not include requirements for reporting specific syntactic errors in the text of a program. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 26373:1989 4 © BSI 01-2000 Implementations conforming to this International Standard may accept programs written in an enhanced language without having to report all constructs not conforming to this International Standard. However, whenever a statement or other program element does not conform to the syntactic rules given herein, either an error shall be reported or the statement or other program element shall have an implementation-defined meaning. An exception occurs when an implementation recognizes that a program may not perform or is not performing in accordance with this International Standard. All exceptions described in this International Standard shall be reported to the user unless some mechanism provided in an enhancement to this International Standard has been invoked by the user to handle exceptions. Where indicated, certain exceptions may be handled by the procedures specified in this International Standard; if no procedure is given, or if restrictions imposed by the hardware or the operating environment make it impossible to follow the given procedures, then the exception shall be handled by terminating the program. Enhancements to this International Standard may describe mechanisms for controlling the manner in which exceptions are reported and handled, but no such mechanisms are specified in this International Standard. This International Standard does not specify an order in which exceptions shall be detected or processed. 3 References ISO 646, Information processing 7-bit coded character set for information interchange1). ISO 4873, Information processing 8-bit coded character set for information interchange. ISO 6093, Information processing Specification for representation of numeric values in character strings for information interchange2). 4 Definitions For the purpose of this International Standard, the following definitions apply. 4.1 BASIC a term applied as a name to members of a special class of languages which possess similar syntaxes and semantic meanings; acronym for Beginners All-purpose Symbolic Instruction Code 4.2 batch-mode the processing of programs in an environment where no provision is made for user interaction 4.3 can the word “can” is used in a descriptive sense to indicate that standard-conforming programs are allowed to contain certain constructions and that standard-conforming implementations are required to process such programs correctly 4.4 end-of-line the character(s) or indicator which identifies the termination of a line. Lines of three kinds may be identified in Minimal BASIC: program lines, print lines, and input-reply lines. End-of-lines may vary between the three cases and may also vary depending upon context. Thus, for example, the end-of-line in an input-reply may vary on a given system depending on the terminal being used in interactive or batch mode typical examples of end-of-line are carriage-return, carriage-return line-feed, and end of record (such as end of card) 4.5 error a flaw in the syntax of a line which causes it not to be part of a standard program 1) At present at the stage of draft. (Revision of ISO 646:1973.) 2) At present at the stage of draft. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 12:43:37 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EN 26373:1989 © BSI 01-20005 4.6 exception a circumstance arising in the course of executing a program which results from faulty data or computations or from exceeding some resource constraint. Where indicated certain exceptions (non-fatal exceptions) may be handled by the specified procedures; if no procedure is given (fatal exceptions) or if restrictions imposed by the hardware or operating environment make it impossible to follow the given procedure, then the exception shall be handled by terminating the program 4.7 identifier a character string used to name a variable or a function 4.8 interactive mode the processing of programs in an environment which permits the user to respond directly to the actions of individual programs and to control the commencement and termination of these programs 4.9 keyword a character string, usually with the spelling of a commonly used or mnemonic word, which provides a distinctive identification of a statement or a component of a statement of a programming language the keywords in Minimal BASIC are: BASE, DATA, DEF, DIM, END, FOR, GO, GOSUB, GOTO, IF, INPUT, LET, NEXT, ON, OPTION, PRINT, RANDOMIZE, READ, REM, RESTORE, RETURN, STEP, STOP, SUB, THEN, and TO 4.10 line a single transmission of characters which terminates with an